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| -rw-r--r-- | ringbuf.h | 79 |
1 files changed, 79 insertions, 0 deletions
diff --git a/ringbuf.h b/ringbuf.h new file mode 100644 index 0000000..6251d6c --- /dev/null +++ b/ringbuf.h @@ -0,0 +1,79 @@ +/* + * ringbuf.h + * --------- + * Ring buffers for more reliable UART receives. + * + * Copyright (c) 2016, NORDUnet A/S All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: + * - Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + * + * - Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * - Neither the name of the NORDUnet nor the names of its contributors may + * be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS + * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED + * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A + * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED + * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR + * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF + * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING + * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#ifndef RINGBUF_SIZE +#define RINGBUF_SIZE 256 +#endif + +typedef struct { + int ridx; + volatile int widx; + uint8_t buf[RINGBUF_SIZE]; +} ringbuf_t; + +inline void ringbuf_init(ringbuf_t *rb) +{ + memset(rb, 0, sizeof(*rb)); +} + +inline int ringbuf_read_char(ringbuf_t *rb, uint8_t *c) +{ + if (rb->ridx != rb->widx) { + *c = rb->buf[rb->ridx]; + if (++rb->ridx >= sizeof(rb->buf)) + rb->ridx = 0; + return 1; + } + return 0; +} + +inline void ringbuf_write_char(ringbuf_t *rb, uint8_t c) +{ + rb->buf[rb->widx] = c; + if (++rb->widx >= sizeof(rb->buf)) + rb->widx = 0; +} + +inline int ringbuf_empty(ringbuf_t *rb) +{ + return (rb->ridx == rb->widx); +} + +inline int ringbuf_count(ringbuf_t *rb) +{ + int len = rb->widx - rb->ridx; + if (len < 0) + len += sizeof(rb->buf); + return len; +} |